June 6, 2003
Algal Bloom of non-toxic Gyrodinium uncatenum causing deep-brown water color in St. Martin River. |
A water sample was collected by the Maryland Department of Natural Resources at the upper St. Martin River continuous monitoring site during routine water quality monitoring on 6/5/2003. The non-toxic dinoflagellate Gyrodinium uncatenum was found blooming at 118,000 cells/ml giving the water a dark chocolate brown appearance. We have a picture of two water samples from the Coastal Bays comparing the water color of the bloom (left) with a sample from a non-bloom location on Turville Creek (right). Evidence of the bloom and its effects on water quality can be seen with the Bishopville Prong Continuous monitoring station data. Dissolved oxygen levels have been swinging between supersaturation near 200% of normal on 6/2/03 through 6/3/03, then declining briefly to 0% on 6/4/03 as the biology of the bloom consumes oxygen to levels unfit for Bay life. The pH levels increase during severe blooms and the data on 6/2/03 and 6/3/03 increase above 8 at the same time chlorophyll levels, an index of the amount of algae in the water rise above 500 ug chlorophyll/L. Values above 100 ug chlorophyll/L are indicative of severe blooms. Comparison
of a sample of the dark brown algal-bloom waters from the Upper St. Martin
River (Station XDM4486) versus non-bloom water of Turville Creek (Station
TUV0016) on June 5, 2003. The concentration in the bloom sample was 118,000
cells/ml of the non-toxic dinoflagellate Gyrodinium uncatenum.
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Maryland Department of Natural Resources, 580 Taylor Avenue, Annapolis, MD 21401
(877) 620-8DNR